The trial of three Russian women who face up to seven years in jail for performing an anti-Vladimir Putin song in a Moscow church got underway proper Monday, in a case that has divided the country.

Initial hearings in the trial earlier this month saw the court order the three members of rock group Pussy Riot to stay in detention until January 2013, a move their supporters condemned as travesty of justice.

With the initial hearings in the trial now over, Monday's audience will see the first legal arguments in a process that is growing into a landmark event in the struggle between President Putin and the emboldened opposition.

The hearing at the packed Khamovnichesky court in Moscow got underway with all three detained present shut in a glass-fronted defendants' box as judge Marina Syrova declared the session open.

In February, the three women climbed into an area reserved for priests in the Church of Christ the Saviour, the country's top Orthodox cathedral, and performed a "punk prayer" against Putin.

The trio -- Nadezhda Tolokonnikova, Yekaterina Samutsevich and Maria Alekhina -- were all arrested in March and charged with hooliganism. Several others also took part but were never arrested.

"This was not a crime. They should not be thrown behind bars. This shows that we are living not in a democratic state as our constitution shows but a police state," said one of their supporters outside the court, Vitaly Zalomov.

Their case has been taken up by celebrities including pop star Sting and US rockers the Red Hot Chili Peppers while some Russian commentators have said the process shows the excessive power of the RussianOrthodox Church.

In an interview with the Times newspaper released by the government on Monday, Prime Minister Dmitry Medvedev called for calm over the case.

"Let us wait for the investigation to be over and the verdict of the court and then we can say if a crime was committed or not," Medvedev said.

He acknowledged: "The case has resonance as it really concerns our understanding of rights and freedoms of individuals." In a significant irony, the Khamovnichesky court is the same court that in 2010 saw the second trial and conviction of Russia's former richest man and Putin foe Mikhail Khodorkovsky on fraud charges.